Wu Qian, Zhou Jingfang, Liu Xiaomeng, Jiang Xingxing, Zhang Qiaoxin, Lin Zheshuai, Xia Mingjun
Beijing Center for Crystal Research and Development, Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China.
Inorg Chem. 2021 Dec 6;60(23):18512-18520. doi: 10.1021/acs.inorgchem.1c03069. Epub 2021 Nov 7.
Intense interests in mid-infrared (MIR) nonlinear optical (NLO) crystals have erupted in recent years due to the development of optoelectronic applications ranging from remote monitoring to molecular spectroscopy. Here, two polar crystals Ca(TeO)(MO) (M = Mo, W) were grown from TeO-MO flux by high-temperature solution methods. Ca(TeO)(MoO) and Ca(TeO)(WO) are isostructural, which feature novel structures consisting of asymmetric MO tetrahedra and TeO trigonal pyramids. Optical characterizations show that both crystals display ultrawide transparency ranges (279 nm to 5.78 μm and 290 nm to 5.62 μm), especially high optical transmittance over 80% in the important atmospheric transparent window of 3-5 μm, and superhigh laser damage thresholds (1.63 GW/cm and 1.50 GW/cm), 54.3 and 50 times larger than that of state-of-the-art MIR NLO AgGaS, respectively. Notably, they exhibit the widest band gaps and the loftiest laser-induced threshold damages among the reported tellurates so far. Moreover, Ca(TeO)(MO) exhibit type I phase matching at two working wavelengths owing to their large birefringence and strong second-harmonic generation responses from the distorted anions, as further elucidated by the first-principles calculations. The above characteristics indicate that Ca(TeO)(MO) crystals are high-performance MIR NLO materials, especially applying in high-power MIR laser operations.
近年来，由于从远程监测到分子光谱等光电应用的发展，人们对中红外（MIR）非线性光学（NLO）晶体产生了浓厚兴趣。在此，通过高温溶液法从TeO-MO助熔剂中生长出两种极性晶体Ca(TeO)(MO)（M = Mo，W）。Ca(TeO)(MoO)和Ca(TeO)(WO)是同构的，其具有由不对称MO四面体和TeO三角锥组成的新颖结构。光学表征表明，这两种晶体都显示出超宽的透明范围（279 nm至5.78 μm和290 nm至5.62 μm），特别是在3-5μm的重要大气透明窗口中具有超过80%的高光学透过率，以及超高的激光损伤阈值（1.63 GW/cm²和1.50 GW/cm²），分别比目前最先进的MIR NLO AgGaS大54.3倍和50倍。值得注意的是，在迄今为止报道的碲酸盐中，它们表现出最宽的带隙和最高的激光诱导阈值损伤。此外，由于Ca(TeO)(MO)具有大的双折射以及来自畸变阴离子的强二次谐波产生响应，通过第一性原理计算进一步阐明，它们在两个工作波长处表现出I型相位匹配。上述特性表明Ca(TeO)(MO)晶体是高性能的MIR NLO材料，尤其适用于高功率MIR激光操作。
